Cheap renewable energy is a major goal of many countries and hardly needs a justification. Not only does renewable energy provide energy independence and security but can often provide carbon neutral or better clean energy. But not all forms of renewable energy are equal. Currently wind, solar, hydro and geothermal power are excellent supplements to the power grid, but cannot be efficiently converted into liquid biofuels needed for our cars, ships and planes. There will be a high demand for biodiesel and other liquid biofuels into the foreseeable future.
Liquid biofuels can be roughly classified by the source (feedstock) and production methods. First generation biofuels like ethanol from corn are now established industries, but the trend is to move away from using food crops as the primary feedstock for energy production. Second generation biofuels like cellulosic ethanol use biomass as the primary feedstock. The biomass is obtained from the “waste” left over after food crops have been processed, or from other energy crops like switchgrass, Miscanthus, and “energycane”. While eliminating the ethical dilemma of tapping into the world's food supply for fuel, cellulosic ethanol is still neither the most efficient way to produce biofuels nor a viable replacement for the majority of the nations fuel needs. Recycling biomass waste into fuel is a great idea, but growing energy crops just to harvest and digest them back into biofuel is not the most efficient use of energy, water, or arable land.
Third generation biofuels have typically been defined as fuels from photosynthetic organisms. The organisms are grown, harvested, and then the fuel precursors are extracted from the biomass. Photosynthetic microbes such as algae and cyanobacteria are the most efficient organisms for solar energy conversion, typically yielding lipids in the range of about 20-30% of dry weight. While photosynthetic microorganisms will theoretically out produce any plant based biofuel systems, costs associated with extraction continue to be a barrier to making these biofuels competitive with fossil fuels.
Hence, there is a need in the art for a microbe capable of producing biofuels or biofuel precursors while decreasing processing and extraction costs.